As a sensor device module which contains a layered metal thin film, devised is a magnetic sensor device module which includes a magnetic resistance thin film layer, formed on the semiconductor substrate thereof. For instance, the structure of a magnetic sensor device module in which a sensor formation field and an integrated circuit which performs predetermined arithmetic processing are arranged on the same plane is disclosed (refer to Patent Document 1, for example). As a foundation layer (insulating film) of the magnetic resistance thin film layer, Si thermal oxidation film is formed. At the next step, a metal electrode (aluminum film) for connecting electrically the integrated circuit and the magnetic resistance thin film layer is formed.
In order to connect the metal electrode and the magnetic resistance thin film layer electrically, a magnetic layer which consists of a Fe(x) Co(1−x) (0≤x≤0.3) layer and a non-magnetic layer which consists of a Cu layer are stacked one above the other, so that the metal electrode may be covered by those layers. At the final step, a protective film is formed. It is to be noted that the magnetic layers which each consists of a Fe(x) Co(1−x) (0≤x≤0.3) layer and the non-magnetic layers which each consists of a Cu layer will become a giant magnetoresistance element (GMR element: Giant Magnetoresistance element). As for other GMR elements, Fe/Cr, Permalloy/Cu/Co/Cu, Co/Cu, and Fe-Co/Cu are disclosed.
Further, disclosed is a structure where an interlayer insulating film is used for flattening a difference in level on the surface of the integrated circuit which performs predetermined arithmetic processing (refer to Patent Document 2, for example). The magnetic sensor device module includes a sensor formation field which is formed right above the integrated circuit. The difference in level on the surface of the integrated circuit is made flat by using a flattening film. At a first step, a silicon nitride film is formed as a foundation layer (insulating film) of the magnetic resistance thin film layer. At the next step, in order to expose the metal electrode of the integrated circuit, a portion of the protective film, the flattening film, and the insulating film is opened, and then a contact hole is formed.
Moreover, metallic wiring is processed on the silicon nitride film, and then a metal electrode is formed. The metal electrode is connected with a metal electrode of the integrated circuit via the contact hole. As the metal electrode, an aluminum film, which is generally used in the present technical field, is used. In order to connect the metal electrode and the magnetic resistance thin film layer electrically, a magnetic layer which consists of a Fe(x) Co(1−x) (0≤x≤0.3) layer and a non-magnetic layer which consists of a Cu layer are stacked one above the other, so that the metal electrode may be covered by those layers. At the final step, a silicon nitride film is formed as a protective film. The magnetic layers which each consists of a Fe(x) Co(1−x) (0≤x≤0.3) layer and the non-magnetic layers which each consists of a Cu layer function as a magnetic resistance thin film layer.
In the above mentioned contact structure of the metal electrode and the magnetic resistance thin film layer, the magnetic resistance thin film layer is comparatively thin with respect to the film thickness of the metal film. Accordingly, the contact structure becomes unstable in electrical connection, and needs to be improved in reliability. For example, in Patent Document 1, a feature of wet etching is employed to form interconnection wiring which is made from an aluminum film. The feature is in that wet etching is isotropic etching, and then, the end of the aluminum film is processed into a tapered shape. At the connection part between the magnetic resistance thin film layer and the aluminum electrode, a cross sectional shape is formed which has an advantage in mechanical stiffness.